Corrosion Resistance of Shape Recoverable Fe-17Mn-5Si-5Cr Alloy in Concrete Structures

The shape memory effect of steel (i.e., Fe-Mn-Si alloys) enables the tensile strengthening of concrete against tensile stress and unexpected structural vibrations. For practical application, the corrosion resistance of shape-memorable Fe-based steel should be verified. In this study, the corrosion resistance of an Fe-based (Fe-16Mn-5Si-4Ni-5Cr-0.3C-1Ti) shape memory alloy (FSMA), a promising candidate for concrete reinforcement, was investigated by comparing it with general carbon steel (S400). The corrosion resistance of FSMA and S400 inserted in a cement mortar was evaluated using electrochemical methods. FSMA has a more stable passive oxide layer in aqueous solutions with various pH values. Thus, the corrosion resistance of the FSMA sample was much higher than that of the S400 carbon steel, which has a passivation layer in strongly alkaline solution. This stable oxide layer reduced the sensitivity of the corrosion resistance of FSMA to changes in the pH, compared to S400. Furthermore, owing to the stable passive oxide layer, FSMA exhibited a higher corrosion resistance in concrete and a lower decrease in corrosion resistance because of the neutralization of concrete. Therefore, FSMA is a promising candidate for providing reinforcement and reparability, resulting in stable and durable concrete.